An ‘electrical machine’ may be a motor or a generator. A generator, for example, typically includes a stator and a rotor. The stator defines a cavity in which the rotor is located and comprises a plurality of coiled wires. The rotor comprises a plurality of magnets and rotates relative to the stator so that electrical energy is induced in the coils of wire.
Typically, the magnets are coupled to an exterior surface of the body of the rotor by an adhesive and a retainer. In operation, the rotor rotates at high speed (i.e. greater than 10,000 rpm), which creates an outwards radial force on the magnets which cannot be retained solely by the adhesive coupling. Consequently, it is necessary to retain the magnets to the body of the rotor using a retainer.
Currently, retainers comprise a metallic sleeve or carbon fibres in a binding resin such as epoxy. The magnets are put into place on the rotor body using a complex jig and then wrapped with resin impregnated carbon fibres, which are then cured to form the retainer.
It is desirable to provide an alternative retainer and method for forming a retainer.